1. Field of the Invention
The present invention relates to an error control method for video bitstream data, and more particularly, to an error control method for video bitstream data encoded according to a data partition technique used in multimedia communication through a wireless channel. This application is based on Korean Patent Application No. 99-42498, filed Oct. 2, 1999, which is incorporated herein by reference.
2. Description of the Related Art
When wire communication media is used for the communication of multimedia data such as video bitstream data, a transmission error rate is very low due to the stability of communication media. However, the transmission error rate in wireless communication is higher than the transmission error rate in wire communication, due to the characteristics of the wireless media. Therefore, controlling errors for securing the reliability of transmission data is very important in wireless multimedia communication. Therefore, the conventional international telecommunication union, telecommunication standardization sector (ITU-T) H.223, is designed in consideration of error resilience in multiplexing various multimedia data. However, in the conventional ITU-T H.223, additional error resilience for the video bitstream data is not considered.
FIG. 1 schematically shows a multiplexing method for packetizing the video bitstream data in the conventional H.223.
As shown in FIG. 1, in the conventional technology, the H.223 adaptation layer-2 (AL-2) is constituted of a portion in which a header 11 is inserted into a video bitstream 10a received from a video codec and a portion in which a cyclic redundancy code (CRC) 12 of 16 bits is added to the video bitstream 10a in order to multiplex and constitute a transmission packet when receiving video bitstream data 10 from a video codec for H.324M such as H.263 or MPEG-4.
Here, the header 11 includes information on the total length of the video bitstream data, a packet number, and information items used for protecting the header. The CRC 12, which is a checksum used for determining an error in the packet, is calculated by performing a polynomial operation on the entire input video bitstream.
The packet constituted in the conventional H.223 AL-2 according to the above method is transmitted to a destination through communication media, and it is checked whether the CRC value of the received packet coincides with the CRC of the transmitted data when the received packet is demultiplexed at the destination. When there is no CRC error, the entire video bitstream data is used for decoding. When there is a CRC error, the entire video bitstream data is not used for decoding and the entire packet is abandoned.
Therefore, according to the conventional method, deterioration of picture quality due to packet loss increases when a communication channel, in which errors occur, such as the wireless channel is used. In particular, in the case of the video bitstream encoded using the data partition technique, even data on a specific partition region in which errors do not occur cannot be used.
In order to solve the above problems, it is an object of the present invention to provide an effective error control method for video bitstream data in wireless multimedia communication, in which a cyclic redundancy code (CRC) is added to each partition region of video bitstream data encoded according to a data partition technique.
It is another object of the present invention to provide a computer program product for the above error control method.
To achieve the first object, according to an aspect of the present invention, there is provided an error control method for video bitstream data used in wireless multimedia communication, comprising the steps of (a) partitioning video bitstream data into units of information items having certain characteristics and encoding the video bitstream data, (b) calculating a checksum for controlling errors in each partitioned unit of the encoded video bitstream data, (c) constituting a packet, in which each checksum calculated in the step (b) is added to the encoded video bitstream data and transmitting the packet through a wireless communication channel, and (d) receiving the packet transmitted in the step (c) and checking whether there is an error in each partitioned unit of the encoded video bitstream data through the checksum of each partitioned unit of the encoded video bitstream data.
According to another aspect of the present invention, there is provided an error control method of video bitstream data in wireless multimedia communication using a packet constituted by adding a checksum for controlling errors to each partitioned unit of video bitstream data, which is partitioned into units of information items having certain characteristics and encoded, comprising the steps of (a) receiving the packet and (b) checking whether errors exist in each partitioned unit of the encoded video bitstream data through the checksum of each partitioned unit of the encoded video bitstream data.
According to another aspect of the present invention, there is provided a method for constituting a packet for controlling errors of a video bitstream data used in wireless multimedia communication, comprising the steps of (a) receiving video bitstream data, which is partitioned into units of information items having certain characteristics and encoded, (b) calculating a checksum for controlling errors in each partitioned unit of the encoded video bitstream data, and (c) constituting a packet by adding each checksum calculated in the step (b) to the encoded video bitstream data.
To achieve the second object, according to an aspect of the present invention, there is provided computer program product, in which programs for executing the steps of (a) receiving video bitstream data, which is partitioned into units of information items having certain characteristics and encoded, and calculating a checksum for controlling errors in each partitioned unit of the encoded video bitstream data and (b) constituting a packet by adding each checksum calculated in the step (a) to the encoded video bitstream data, by computers, are recorded.
According to another aspect of the present invention, there is provided computer program product, in which programs for executing the steps of (a) receiving the packet and (b) checking whether there are errors in each partitioned unit of the encoded video bitstream data through the checksum of each partitioned unit of the encoded video bitstream data, by computers, are recorded in order to control errors of video bitstream data using a packet constituted by adding a checksum for controlling errors to each partitioned unit of video bitstream data, which is partitioned into units of information items having certain characteristics and encoded.
According to another aspect of the present invention, there is provided computer program product, in which programs for executing the steps of (a) receiving video bitstream data, which is partitioned into units of information items having certain characteristics and encoded, and calculating a checksum for controlling errors in each partitioned unit of the encoded video bitstream data, (b) constituting a packet, in which each checksum calculated in the step (a) is added to the encoded video bitstream data, and transmitting the packet through a wireless communication channel, and (c) receiving the packet of the encoded video bitstream data and checking whether there is an error in each partitioned unit of the encoded video bitstream data through the checksum of each partitioned unit of the encoded video bitstream data, by computers, are recorded.